Women With A Berry-Snacking Habit May Have Healthier Hearts

Regular consumption of blueberries, such as these found at Butler's Orchard in Maryland, may prevent heart attacks in middle-aged women.

Maggie StarbardNPR

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Originally published on January 15, 2013 10:08 am

When it comes to supernutritious foods, the blueberry has long had a health halo floating over it.

Going back to Colonial times when Native Americans and English settlers ground up blueberries and added them to porridge, in both dried and fresh forms, there have been hints of health-promoting effects.

Now, a new study published in the American Heart Association's journal Circulation suggests eating three servings per week of blueberries and strawberries helps cut the risk of heart attacks among some women.

"We showed for the first time that a regular intake of substances that are naturally present in red-, blue-colored fruits and vegetables can reduce the risk of a heart attack by about 32 percent in young and middle-aged women [ages mid-40s to 60]," compared with women who ate berries once a month or less, says study author Aedin Cassidy of the University of East Anglia. The researchers found other fruits such as apples and pears were not associated with a decreased risk.

To study the relationship between berry consumption and heart disease, Cassidy and her collaborators at the Harvard School of Public Health analyzed findings from the Nurses Health Study 2 which includes more than 90,000 nurses in the U.S. Periodically over the past 18 years the nurses have reported details about their diets and lifestyles to researchers. At the same time, researchers have monitored the nurses' health to see which diseases they go on to develop, or not.

It's certainly not a perfect way to detect how certain foods may influence health, but it identifies important associations. Cassidy says the association between berry consumption and heart disease was strengthened when she and her collaborators controlled for other reasons that could have explained the finding.

"Even when we adjusted for things like fat intake, fiber intake, medication use, or body size, and for example, exercise, we still got these strong reductions in risk," Cassidy says.

So what's in blueberries that makes them so good for us? Researchers have pinpointed a class of plant compounds known as anthocyanins. These compounds give the red and blue color to everything from berries to eggplants to cherries. And when you eat a steady diet of them, they seem to have a number of positive health effects.

"They have effects on blood pressure in animal models," says Cassidy. And in lab experiments they're shown to exert anti-inflammatory effects, as well as help modulate nitric oxide in the body, which could help arteries stay more elastic and flexible.

All of these effects could be beneficial, explains Robert Eckel, a preventive cardiologist at the University of Colorado. But he says it's important to point out that the women in this study weren't prime candidates for heart attacks anyway.

"Having a heart attack when you're a woman between ages of 45 and 60 is distinctly unusual," says Eckel.

Would the protective effect hold up for older women? Eckel says it's not clear.

"But nonetheless, for the first time I think we have some evidence that the intake of theses anthocyanins may have a protective effect."

So, go ahead. Load up on berries. And if they're out of season, like now, studies show frozen berries have similar levels of beneficial compounds.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

AUDIE CORNISH, HOST:

When it comes to staying healthy, most of us know we're supposed to eat our five a day. But not all fruits and veggies were created nutritionally equal. New evidence today suggests some may give us more bang for our buck.

NPR's Allison Aubrey reports on a study that finds women who ate at least three servings per week of blueberries and strawberries, had fewer heart attacks.

ALLISON AUBREY, BYLINE: When it comes to foods that are thought to be supernutritious, the blueberry has long had a health halo floating over it. Going back centuries, when blueberries grew wild all over American colonies, foodways historian Kathleen Wall says they were considered an important part of the diet.

KATHLEEN WALL: Going back to Colonial times, Native Americans and the English colonists were eating blueberries. They were drying them. They would pound them into a paste. They would add them to their porridge.

AUBREY: Not so different from us topping off our oatmeal with berries. Now, Native Americans may have had some clues and beliefs about the health-promoting effects of berries. But it's only in recent years that scientists have started to really try to nail them down. For instance, research suggests that berry consumption may be good for the brain. And one large study links berries to a decreased risk of Type 2 diabetes.

Today, researchers add another finding to the growing body of evidence. A study published in the journal "Circulation" finds blueberries, as well as strawberries, seem to help cut the risk of heart disease in some women. Aedin Cassidy, of the University of East Anglia, is the study author.

AEDIN CASSIDY: We showed, for the first time, that a regular intake of substances that are naturally present in red-, blue-colored fruits and vegetables can reduce the risk of a heart attack by about 32 percent, in young and middle-aged women.

AUBREY: The findings come from the huge Harvard study of some 90,000 nurses in the U.S., who for years have reported details about their diets and lifestyles to researchers. At the same time, researchers have monitored the nurses' health, to see which diseases they go on to develop - or not. It's certainly not a perfect way to detect how certain foods may influence health. But Cassidy says in this instance, the association was strengthened when she ruled out other reasons that the blueberry-eating nurses didn't have heart attacks.

CASSIDY: Even when we adjusted for things like fat intake, fiber intake or medication use; or body size and, for example, exercise; we still got the strong reductions in risk.

AUBREY: So what is it about berries that could explain such an effect? In lab experiments, researchers have pinpointed a class of plant compounds, known as anthocyanins. They give the red and blue color to everything from berries to eggplants to cherries. And Cassidy says when you eat a lot of them, they seem to work in a number ways.

CASSIDY: They have effects on blood pressure in animal models. And they do things like exert anti-inflammatory effects, for example.

AUBREY: Which may help keep arteries more elastic and flexible. Dr. Robert Eckel, a preventive cardiologist at the University of Colorado, says that's a good thing. But he says there is a caveat here. The women in this study were not prime candidates for heart attacks.

DR. ROBERT ECKEL: Having a heart attack when you're a woman between the ages of 45 and 60, is distinctly unusual.

AUBREY: So does the protective effect hold up for older women? Eckel says it's not clear.

ECKEL: But nevertheless, for the first time, I think we have some evidence that the intake of these anthocyanins may have a protective effect.

AUBREY: So, Eckel says, go ahead - add in more berries. It can't hurt. And if they're out of season - like now - studies show frozen berries have similar levels of beneficial compounds.